<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>



<script>

  function SuperType(){
    this.property = true;
  }

  SuperType.prototype.getSuperValue = function(){
    return this.property;
  };

  function SubType(){
    this.subproperty = false;
  }

  SubType.prototype = new SuperType();
  SubType.prototype.getSubValue = function (){
    return this.subproperty;
  };

  var instance = new SubType();
  console.log(instance.getSuperValue()); // true
</script>
</body>
</html>
